JP4866797B2 - Swivel control device for construction machinery - Google Patents

Description

  The present invention relates to a turning control device for a construction machine having a make-up circuit for supplying hydraulic oil to a turning motor.

  In a construction machine such as a hydraulic excavator, a turning motor is connected via a make-up circuit in order to prevent the inflow side conduit of the turning motor from becoming negative pressure due to the turning body turning with inertial force when the turning is stopped. There is known a swivel hydraulic circuit that can supply hydraulic oil to the inflow side pipeline (see, for example, Patent Document 1). In the circuit described in Patent Document 1, a make-up circuit is formed using a return oil path from a swing motor to a tank, and a variable throttle valve is interposed in the return oil path, and the pressure of the make-up circuit is set by the variable throttle valve. The make-up oil is supplied to the inflow side conduit of the turning motor.

Japanese Patent No. 3113500

  By the way, in this type of construction machine, it may be difficult to form a make-up circuit using the return oil path of the swing motor because of piping layout. In this case, the return oil path of other hydraulic actuators Is used to form a makeup circuit. However, if a make-up circuit is formed by using a return oil passage of another hydraulic actuator, for example, during a turning operation alone, there is a possibility that a sufficient back pressure for supplying sufficient make-up oil may not be ensured.

A turning control device for a construction machine according to the present invention includes a first hydraulic pump, a turning hydraulic motor driven by pressure oil from the first hydraulic pump to turn a turning body, and turning from the first hydraulic pump. A first hydraulic circuit including a first control valve for controlling the flow of pressure oil to the hydraulic motor, a second hydraulic pump, and a hydraulic actuator other than for turning driven by pressure oil from the second hydraulic pump And a second hydraulic circuit including a second control valve for controlling the flow of pressure oil from the second hydraulic pump to the hydraulic actuator, and the inflow side of the turning hydraulic motor from the return oil path of the second hydraulic circuit Make-up circuit for supplying oil to the pipeline, first operating lever for instructing driving of the turning hydraulic motor, first detecting means for detecting operation of the first operating lever, and first detecting means Detects turning operation. And a flow rate control means for increasing the amount of oil flowing through the second hydraulic circuit and then decreasing the amount of oil flowing through the second hydraulic circuit with a delay when a return operation to the neutral position is detected thereafter. It is characterized by.
The second hydraulic pump is configured as a variable displacement hydraulic pump driven by a prime mover, and the tilt angle that increases the tilt angle of the second hydraulic pump when the turning operation is detected by the first detecting means. Control means can also be provided.
In this case, when the turning operation is detected by the first detection means, the pump tilt angle is increased, and then when the return operation to the neutral position is detected, the pump tilt angle may be gradually decreased. preferable.
As the turning operation amount detected by the first detection means increases, the pump tilt angle may be increased during the turning operation.
A second operating lever for instructing driving of the hydraulic actuator; and a second detecting means for detecting an operation of the second operating lever; and a second operating lever according to the operation detected by the first detecting means. A first tilt calculation circuit that calculates a target tilt angle of the hydraulic pump, and a second calculation circuit that calculates a target tilt angle of the second hydraulic pump according to an operation detected by the second detection means The pump tilt angle is controlled to the larger value of the target tilt angle calculated by the first tilt calculation circuit and the target tilt angle calculated by the second tilt calculation circuit. You may make it do.
It is also possible to provide a valve unit in which a plurality of second control valves are assembled at the center of the revolving structure, and to provide the first control valve away from the valve unit.

  According to the present invention, when a make-up circuit of a turning motor is connected to a second hydraulic circuit different from the first hydraulic circuit for turning, and the turning operation is detected, the oil flowing through the second hydraulic circuit The amount of oil flowing in the second hydraulic circuit is delayed and decreased when a return operation to the neutral position is detected after that. Can supply.

Hereinafter, an embodiment of a turning control device for a construction machine according to the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a hydraulic excavator that is an example of a construction machine having a turning control device according to the present embodiment. In addition, the front-rear and left-right directions of the hydraulic excavator are defined as shown in the figure, and the arrangement of each part will be described according to this definition below.

  The hydraulic excavator in FIG. 1 is a large hydraulic excavator having a vehicle body weight exceeding 100 t, for example, and includes a traveling body 1 and a revolving body 2 that can pivot with respect to the traveling body 1. A work device mounting bracket 3 is provided at the front portion of the swing body 2, and a counterweight 4 is mounted at the rear end portion of the swing body 2. Although not shown in the drawings, the working device includes a pivotable boom, arm, bucket, and the like, and the working device is driven by an operation in the cab to perform excavation work. The boom, arm, and bucket are driven by a boom cylinder 32, an arm cylinder 31, and a bucket cylinder 33 in FIG.

  FIG. 2 is a plan view showing a layout of components on the swing body 2. As shown in FIGS. 1 and 2, a cab 5 is provided on the left side of the bracket 3. A hydraulic oil tank 7 is installed behind the cab 5, and an engine compartment 6 whose periphery is covered with a cover is formed behind the hydraulic oil tank 7. Between the hydraulic oil tank 7 and the engine room 6, a walking path 8a for maintenance is formed in the left-right direction.

  A passage entrance door 9 is provided at the left end of the passage 8a, and an oil cooler 11 and a cooling fan 12 are disposed at the right end. The cooling fan 12 is driven by a hydraulic motor 13. A fuel tank 10 is installed in front of the oil cooler 11. A walking passage 8b for maintenance is formed between the fuel tank 10 and the cab 5 in the front-rear direction. A center joint 17 is provided in front of the passage 8a and on the left side of the passage 8b.

  An engine 20 is disposed in the engine chamber 6 in the left-right direction. A cooling fan 16 is disposed on the right side of the engine 20, and a hydraulic pump 14 is disposed on the left side of the engine 20. The cooling fan 16 and the hydraulic pump 14 are connected to the output shaft of the engine 20, and these are driven by the engine 20. A radiator 15 is disposed on the right side of the engine 20 so as to face the cooling fan 16.

  A valve unit 21 (FIG. 3) including a plurality of control valves for controlling the flow of hydraulic oil is disposed in front of the passage 8 a and behind the center joint 17, that is, substantially in the center of the revolving structure 2. The valve unit 21 is diverted to a medium-sized hydraulic excavator with a vehicle body weight of 40t to 80t class. When diverted to a medium-sized hydraulic excavator, the valve unit 21 is used for driving a working device, for traveling, and for turning. Each control valve for is incorporated.

  On the other hand, in the large hydraulic excavator as in the present embodiment, when the control valves for driving the working device, for traveling, and for turning are incorporated in the valve unit 21, a predetermined working flow rate (for example, turning flow rate) is obtained. There may be a shortage. Therefore, in the present embodiment, the control valve 22 for turning is not incorporated in the valve unit 21, but is arranged in an extra space between the oil tank 7 and the passage 8a apart from the valve unit 21. That is, the turning control valve 22 is configured separately from the valve unit 21 so as to ensure a sufficient turning flow rate.

  FIG. 3 is a hydraulic circuit diagram for driving the hydraulic excavator showing the configuration of the turning control device according to the present embodiment. The hydraulic pump 14 has a pair of main pumps 141 and 142 and a turning pump 143, which are driven by the engine 20. The pumps 141 to 143 are variable displacement pumps, and the pump tilt angle is controlled by a control signal from the controller 50 as described later.

  The valve unit 21 includes a pair of control valves 211 and 212 for driving an arm cylinder, a pair of control valves 213 and 214 for driving a boom cylinder, a pair of control valves 215 and 216 for driving a bucket cylinder, Control valves 217 and 218 for driving the traveling motor are provided. The control valves 211, 213, 215, and 217 are connected in series to the main pump 141, and the control valves 212, 214, 216, and 218 are connected in series to the main pump 142. An oil cooler 11 is provided in the return oil passage 41 from the valve unit 21 to the tank 7. On the other hand, the turning control valve 22 is not incorporated in the valve unit 21 but is connected to the turning pump 143 alone.

  The control valves 211 and 212 are operated by the operating lever 25, the control valves 213 and 214 are operated by the operating lever 26, the control valves 215 and 216 are operated by the operating lever 27, the control valve 217 is operated by the operating lever 28, The control valve 218 is operated by the operation lever 29, and the control valve 22 is operated by the operation lever 30. That is, the control valves 211 to 218 and 22 are respectively switched by the pilot pressure from the pilot pump 23 according to the operation of the operation levers 25 to 30. Thereby, the arm cylinder 31, the boom cylinder 32, the bucket cylinder 33, the left and right traveling motors 34 and 35, and the turning motor 36 are driven.

The pressure oil inflow side line 36 a or 36 b of the swing motor 36 is connected to the make-up port 21 a of the valve unit 21 via the check valve 37 and the make-up line 38. The makeup port 21a communicates with the return oil passage 41 in the valve unit 21, and a makeup circuit is formed from the return oil passage 41 to the motor inflow side conduits 36a and 36b. Thus the control valve 22 return oil passage 4 2 from the motor inlet side conduit 36a, there is no need to form a make-up circuit toward 36b, piping layout is facilitated on the swing body 2. The make-up port 21a is originally provided in the valve unit 21 itself, and by using the valve unit 21, a make-up circuit can be formed without newly adding a make-up port.

  In the hydraulic circuit configured as described above, when the operation lever 30 is turned, the control valve 22 is driven according to the amount of operation, and the hydraulic oil is supplied from the hydraulic pump 143 to the turning motor 36 to drive the turning motor 36. . Thereafter, when the operation lever 30 is returned to the neutral position (turning stop operation), the control valve 22 is switched to the neutral position, and the supply of pressure oil from the hydraulic pump 143 to the turning motor 36 is blocked. During this turning stop operation, the turning body 2 keeps turning by inertia force without suddenly stopping. For this reason, the swing motor 36 acts as a pump, and oil is sucked into the motor inflow side pipelines 36a and 36b via the return oil passage 41, the makeup pipeline 38, and the check valve 37, and makeup oil is replenished. .

  At this time, if the tilt angle of the main pumps 141 and 142 is increased as the operation amount of the operation levers 25 to 29 is increased, for example, when the operation lever 30 is operated alone, there are the following problems. . That is, if the control lever 30 is operated alone, all the control valves 211 to 218 in the valve unit are switched to the neutral position, so that the amount of oil flowing through the return oil passage 41 is small and a sufficient makeup flow rate may not be ensured. On the other hand, if a relief valve is provided in the return oil passage 41 to increase the back pressure in order to ensure the makeup flow rate, the number of parts increases. In addition, it is difficult to provide a relief valve in the return oil passage 41 in terms of space. Therefore, in this embodiment, in order to ensure a sufficient makeup flow rate, the back pressure is increased by increasing the flow rate by controlling the pump tilt angle as described later.

  A pressure sensor 51 is connected to the pilot line that supplies the pilot pressure to the control valve 22, and the operation (operation pressure Pi) of the operation lever 30 is detected by the pressure sensor 51. Although not shown, a pressure sensor 51 is similarly connected to a pilot pipe that supplies pilot pressure to the control valves 211 to 218, and the operation of the operation levers 25 to 29 (operation pressure Pi) is performed by each pressure sensor 51. Detected. A signal from each pressure sensor 51 is input to the controller 50, and the regulators 141a to 143a are driven by the signal from the controller 50 to control the pump tilt angle.

  FIG. 4 is a diagram illustrating a configuration of the regulator 141a. The other regulators 142a and 143a have the same configuration as that shown in FIG. As shown in FIG. 4, the discharge pressure Pp of the main pump 141 acts on the small diameter side oil chamber 202 a of the piston 202 via the check valve 201 and also acts on the inlet side port of the spool 203. Further, the pressure oil from the pilot pump 204 is decompressed by the electromagnetic proportional pressure reducing valve 205, acts on the pilot piston 206, and merges with the discharge oil of the main pump 141 via the check valve 207. As a result, the spool 203 is driven according to the degree of pressure reduction of the electromagnetic proportional pressure reducing valve 205, the control pressure acting on the large-diameter side oil chamber 202b of the piston 202 changes, and the pump tilt angle q changes. The pump discharge pressure Pp is detected by the pressure sensor 52 and input to the controller 50.

  FIG. 5 is a block diagram for explaining processing in the controller 50 related to tilt control of the main pump 141. In the figure, reference numerals 51A to 51C denote pressure sensors 51 that detect operations of the operation levers 26, 27, and 30, that is, boom operations, bucket operations, and turning operations, respectively. In addition, illustration is abbreviate | omitted about the pressure sensor 51 which detects arm operation and driving | running | working operation.

  A signal Pp (pump discharge pressure) from the pressure sensor 52 is input to the tilt calculation circuit 53. In the tilt calculation circuit 53, a constant Pq characteristic as shown in the figure is stored in advance so that the absorption torque of the pump 141 does not exceed the output torque of the engine 20. In the tilt calculation circuit 53, a target tilt angle qa corresponding to the signal Pq of the pressure sensor 52 is calculated.

  A signal Pi (boom operation pressure) from the pressure sensor 51A is input to the tilt calculation circuit 54A, and a signal (bucket operation pressure) from the pressure sensor 51B is input to the tilt calculation circuit 54B. In the tilt calculation circuits 54A and 54B, the pump tilt increases proportionally from the minimum value qmin to the maximum value qmax until the operating pressure Pi (so-called positive control pressure) reaches 0 to a predetermined value P1, and the operating pressure Pi is increased. A characteristic is stored such that the pump tilt becomes the maximum value qmax at a predetermined value P1 or more. In the tilt calculation circuits 54A and 54B, target tilt angles qb corresponding to the signals from the pressure sensors 51A and 51B are calculated. Although not shown, the target tilt angle qb is similarly calculated for the arm operation and the traveling operation.

  The delay processing circuit 55 outputs a first-order delay signal Px as indicated by a solid line with respect to the input signal Pi (turning operation pressure) of the pressure sensor 51C indicated by a dotted line. The primary delay signal Px is input to the tilt calculation circuit 56. In the tilt calculation circuit 56, the pump tilt increases proportionally from the minimum value qmin to the predetermined value qs until the operating pressure Pi reaches 0 to a predetermined value P1, and the pump tilts when the operating pressure Pi exceeds the predetermined value P1. Is stored so as to have a predetermined value qs. In the tilt calculation circuit 56, a target tilt angle qx corresponding to the primary delay signal Px of the turning operation pressure is calculated. The target tilt angle qx functions as a variable for generating a makeup pressure in the return oil circuit 41 at the time of turning stop operation, and the predetermined value qs is a value (for example, a maximum value) that can ensure a sufficient makeup flow rate. Value qmax).

  The maximum value selection circuit 57 selects the maximum values of the target tilt angles qb and qx calculated by the tilt calculation circuits 54A, 54B, and 56. That is, the maximum value is selected from the target tilt angle qb corresponding to the boom operation, the arm operation, the bucket operation, and the traveling operation and the first-order delay target tilt angle qx corresponding to the turning operation, and this is selected as the target tilt angle. Output as qc.

  The minimum value selection circuit 58 selects a smaller one of the target tilt angle qa calculated by the tilt calculation circuit 53 and the target tilt angle qc selected by the maximum value selection circuit 57, and this is selected as the target. Output as tilt angle q. The signal generation circuit 59 calculates a control signal I corresponding to the target tilt angle q according to a predetermined characteristic as shown in the figure, and outputs this to the electromagnetic proportional pressure reducing valve 205 of the regulator 141a. As a result, the pump tilt angle of the main pump 141 is controlled to the target tilt angle q. The tilt angle control of the main pump 142 is also performed in the same manner as in FIG.

  FIG. 6 is a block diagram for explaining processing in the controller 50 relating to the tilt control of the turning pump 143. A signal Pp (pump discharge pressure) from the pressure sensor 52 is input to the tilt calculation circuit 53, and a target tilt angle qa corresponding to the signal Pq from the pressure sensor 52 is calculated. A signal Pi (turning operation pressure) from the pressure sensor 51C is input to the tilt calculation circuit 54C. The tilt calculation circuit 54C has characteristics similar to those of the tilt calculation circuits 54A and 54B of FIG. 5, and the target tilt angle qb is calculated according to these characteristics. The minimum value selection circuit 58 selects the smaller one of the target tilt angles qa and qb and outputs this as the target tilt angle q. The signal generation circuit 59 calculates the control signal I corresponding to the target tilt angle q and outputs it to the electromagnetic proportional pressure reducing valve 205 of the regulator 143a. As a result, the pump tilt angle of the turning pump 143 is controlled to the target tilt angle q.

A characteristic operation of the present embodiment will be described.
(1) Turning operation For example, when the turning operation lever 30 is operated alone (turning operation), the tilt calculation circuit 54C outputs a target tilt angle qb corresponding to the operation amount (FIG. 6). As a result, the tilt angle of the turning pump 143 is controlled to the target tilt angle q (= qb). At this time, the control valve 22 is switched according to the operation amount of the operation lever 30, the discharge oil of the turning pump 143 is supplied to the turning motor 36, the turning motor 36 rotates, and the turning body 2 turns. When the target tilt angle qb is larger than the target tilt angle qa output from the tilt calculation circuit 53, the tilt angle of the turning pump 143 is controlled to the target tilt angle qa.

  When the operation lever 30 is operated alone, the tilt calculation circuit 56 outputs a target tilt angle qx with a first-order lag corresponding to the operation amount (FIG. 5). At this time, since the minimum value qmin is output from the tilt calculation circuits 54A and 54B, the maximum value selection circuit 57 selects the target tilt angle qx. As a result, the tilt angle of the main pumps 141 and 142 is controlled to the target tilt angle q (= qx), and the discharge oil of the main pumps 141 and 421 passes through the valve unit 21 and the amount of return oil to the tank 7 increases. To do. When the target tilt angle qx is larger than the target tilt angle qa output from the tilt calculation circuit 53, the tilt angles of the main pumps 141 and 142 are controlled to the target tilt angle qa.

  When, for example, the boom drive operation lever 25 is operated simultaneously with the operation lever 30, the tilt calculation circuit 54A outputs a target tilt angle qb corresponding to the operation amount. In this case, the tilt angle of the main pumps 141 and 142 is controlled to a larger value between the target tilt angles qx and qb, and the discharged oil of the main pumps 141 and 142 is boomed via the control valves 215 and 216. It is supplied to the cylinder 33.

(2) Turning stop operation When the operation lever 30 is turned alone, when the operation is returned to the neutral position (turning stop operation), the minimum value qmin is output as the target tilt angle qb from the tilt calculation circuit 54C. The tilt angle of the turning pump 143 is controlled to the target tilt angle qmin. At this time, the control valve 22 is switched to the neutral position, and the flow of oil from the turning pump 143 to the turning motor 36 is blocked. However, the turning body 2 does not stop suddenly and continues to turn due to inertial force. As a result, the swing motor 36 acts as a pump, and makeup oil is sucked into the inflow side pipes 36 a and 36 b of the swing motor 36 via the makeup circuit 38.

  During the turning stop operation, the tilt calculation circuit 56 outputs a target tilt angle qx with a first-order lag. For this reason, the tilt angle q of the main pumps 141 and 142 does not immediately become the minimum value qmin, but the tilt angle q gradually decreases with time. As a result, at the time of turning stop operation, the discharge amount of the main pumps 141 and 142 increases compared to when the operation lever 30 is not operated, the amount of oil flowing through the return oil passage 41 increases, and back pressure is generated. For this reason, sufficient make-up oil can be supplied to the motor inflow side pipelines 36a and 36b. In this case, the higher the turning speed, that is, the larger the turning operation amount of the operation lever 30, the more makeup oil is required at the time of turning stop operation. However, in the tilt angle calculation circuit 56, the operation amount of the operation lever 30 is large. As the target tilt angle qx is increased, an appropriate makeup oil corresponding to the turning speed can be supplied.

According to the present embodiment, the following operational effects can be achieved.
(1) A make-up line 38 of the swing motor 36 is connected to the make-up port 21a of the valve unit 21 that controls the flow of the discharged oil of the main pumps 141 and 142, and the target tilt of the first order lag when the stop operation is performed. The angle qx is output, and the discharge amounts of the main pumps 141 and 142 are reduced with a delay. This increases the amount of oil flowing through the return oil passage 41 during the turning stop operation and generates back pressure, so that sufficient makeup oil can be supplied to the inflow side conduits 36a and 36b of the turning motor 36.

(2) Since the primary tilt target tilt angle qx is output at the time of turning stop operation and the pump tilt angle q is gradually reduced, if the turning speed decreases with time after turning stop operation, the return oil passage 41 The amount of oil flowing through gradually decreases. For this reason, it is not necessary to return the oil to the return oil passage 41 more than necessary, which is efficient.
(3) Since the target tilt angle qx having a first order delay with respect to the operation of the operation lever 30 is output, the pump tilt angle changes following the operation of the operation lever 30, and the pump tilt angle can be efficiently controlled. .
(4) Since the target tilt angle qx is increased as the operation amount of the operation lever 30 is increased, an appropriate amount of makeup oil corresponding to the inertial force of the revolving structure 2 can be supplied during the turning stop operation.

(5) When the boom operation or the arm operation is performed simultaneously with the turning operation, the pump tilt angle q is controlled to the maximum value of the target tilt angles qb and qx corresponding to each operation. Can be performed satisfactorily.
(6) Since the control valve 22 for turning is provided separately from the valve unit 21, a sufficient turning flow rate can be secured in a large hydraulic excavator.
(7) Since the valve unit 21 used in the medium-sized hydraulic excavator is diverted, it is not necessary to newly provide a valve unit, and the cost can be reduced.
(8) A makeup circuit can be easily formed by simply connecting the makeup line 38 to the makeup port 21a of the valve unit 21.

  In the above embodiment (FIG. 3), the turning hydraulic circuit (first hydraulic circuit) is constituted by the turning pump 143 (first hydraulic pump), the turning motor 36 and the control valve 22 (first control valve). ), And a hydraulic circuit for driving the hydraulic actuator (the second hydraulic pump), hydraulic actuators 31 to 35 other than the swing motor, and control valves 211 to 217 (second control valves) The second hydraulic circuit) is formed, but the hydraulic circuit configuration is not limited to this. A makeup circuit 38 is formed by connecting a makeup line 38 to the makeup port 21a of the valve unit 21, but the inflow side lines 36a and 36b of the turning motor 36 are connected to the return oil path of the hydraulic circuit for driving the hydraulic actuator. If makeup oil is supplied to, the structure of a makeup circuit is not restricted to this.

  By detecting the operation of the turning operation lever 30 (first operation lever) by the pressure sensor 51C as the first detecting means, and outputting a control signal to the pressure reducing valve 205 at the time of turning stop operation, the main pump 141, Although the pump tilt angle 142 is increased and the oil amount in the return oil passage 41 is increased, the configuration of the tilt angle control means is not limited to this. Only the tilt angle of one of the main pumps 141 and 142 may be increased. Although the oil amount of the return oil passage 41 is increased during the turning operation, it may not be increased during the turning operation as long as the return oil amount is increased at least during the turning stop operation. Although the delay processing circuit 55 performs the first-order delay processing of the turning operation pressure Pi and decreases the amount of return oil at the time of turning stop operation, the flow rate control means is not limited to this. The return oil amount may be increased by controlling other than the pump tilt angle.

  The tilt calculation circuit 56 (first tilt calculation circuit) calculates the target tilt angle qx of the main pumps 141 and 142 according to the turning operation detected by the pressure sensor 51A, and the tilt calculation circuit 54A, The main pump 141 according to the operation of the other operation levers 25 to 29 (second operation lever) detected by the pressure sensors 51A and 51B (second detection means) in 54B (second tilt calculation circuit). 142, the pump tilt angle is controlled to the larger value qc of the target tilt angles qb and qx, but the processing in the controller 50 is not limited to this.

  In the above embodiment, the valve unit 21 is arranged at the center of the revolving structure 2 and the control valve 22 is arranged away from the valve unit 21. However, the arrangement of the control valve 22 is not limited to this. The example in which the turning control device is applied to a particularly large hydraulic excavator has been described above, but the present invention can be applied to other construction machines as well. That is, the present invention is not limited to the turning control device of the embodiment as long as the features and functions of the present invention can be realized.

1 is a perspective view of a hydraulic excavator having a turning control device according to the present embodiment. The top view which shows schematically the structure of the turning body of FIG. The hydraulic circuit diagram which shows the structure of the turning control apparatus which concerns on this Embodiment. The figure which shows the structure of the regulator of FIG. The block diagram which shows the structure of the controller which concerns on the tilt control of a main pump. The block diagram which shows the structure of the controller which concerns on the tilt control of the pump for rotation.

Explanation of symbols

21 Valve unit 22 Control valve 25-30 Operation lever 32 Boom cylinder 36 Swing motor 38 Make-up line 41 Return oil path 50 Controller 51 Pressure sensor 55 Delay processing circuit 56 Tilt calculation circuit 57 Maximum value selection circuit 141, 142 Main pump 141a, 142a Regulator 143 Swivel pump 205 Pressure reducing valve

Claims (6)

The first hydraulic pump, the turning hydraulic motor driven by the pressure oil from the first hydraulic pump to turn the turning body, and the flow of pressure oil from the first hydraulic pump to the turning hydraulic motor A first hydraulic circuit including a first control valve to control;
A second hydraulic pump, a hydraulic actuator other than a swivel driven by pressure oil from the second hydraulic pump, and a second control for controlling the flow of pressure oil from the second hydraulic pump to the hydraulic actuator A second hydraulic circuit including a valve;
A makeup circuit for supplying oil from a return oil passage of the second hydraulic circuit to an inflow side conduit of the turning hydraulic motor;
A first operating lever that commands driving of the turning hydraulic motor;
First detecting means for detecting operation of the first operating lever;
When the turning operation is detected by the first detection means, the amount of oil flowing through the second hydraulic circuit is increased, and then when the return operation to the neutral position is detected, the second hydraulic circuit is turned on. A turn control device for a construction machine, comprising flow rate control means for reducing the amount of flowing oil with a delay. The turning control device for a construction machine according to claim 1,
The second hydraulic pump is a variable displacement hydraulic pump driven by a prime mover,
The flow control means has a tilt angle control means for increasing a tilt angle of the second hydraulic pump when a turning operation is detected by the first detection means. Control device. The turning control device for a construction machine according to claim 2,
The tilt angle control means increases the pump tilt angle when the turning operation is detected by the first detecting means, and then detects the pump tilt angle when the return operation to the neutral position is detected. A turning control device for a construction machine characterized by being gradually reduced. In the turning control device of the construction machine according to claim 2 or 3,
The turning control device for a construction machine, wherein the tilt control means increases the pump tilt angle during the turning operation as the turning operation amount detected by the first detection means increases. In the turning control device of the construction machine according to any one of claims 2 to 4,
A second operating lever that commands driving of the hydraulic actuator;
A second detecting means for detecting an operation of the second operating lever;
The tilt angle control means includes:
A first tilt calculation circuit that calculates a target tilt angle of the second hydraulic pump according to an operation detected by the first detection means;
A second arithmetic circuit that calculates a target tilt angle of the second hydraulic pump according to an operation detected by the second detection means;
The pump tilt angle is controlled to a larger value between the target tilt angle calculated by the first tilt calculation circuit and the target tilt angle calculated by the second tilt calculation circuit. A swing control device for a construction machine. In the turning control device of the construction machine according to any one of claims 1 to 5,
In the central part of the swivel body, a valve unit comprising a plurality of the second control valves is provided,
The swing control device for a construction machine, wherein the first control valve is provided apart from the valve unit.

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